18 gauge steel thickness
18 gauge sheet steel is 0.0478 inches thick, or 1.21 mm. It weighs 1.95 lb per square foot, so a standard 4×8 sheet comes in around 62 lb.
Inches
0.0478"
Millimetres
1.21 mm
Weight
1.95 lb/ft²
4×8 sheet
62 lb
What 18 gauge is used for
Enclosures, cabinets, HVAC plenums, and light architectural panels. Forms cleanly on a press brake.
18 gauge in other materials
Sheet steel
0.0478"
Galvanized
0.0516"
Stainless
0.0500"
Galvanized and stainless use their own gauge series — the same gauge number is a different thickness in each. Reading a galvanized order off a plain steel chart is one of the most common ordering mistakes in the shop.
Next gauge up and down
Thicker — 17 gauge
0.0538"
13% thicker than 18 gauge
Thinner — 19 gauge
0.0418"
13% thinner than 18 gauge
Calculate a 18 gauge order
Gauge converter
Inches
0.0478"
Millimetres
1.21 mm
Weight
1.95 lb/ft²
Total
195 lb
Weight is calculated at 40.84 lb/ft² per inch of thickness. The Manufacturers' Standard Gauge quotes a nominal 2.00 lb/ft² for 18 gauge, based on a historical wrought-iron density — if a mill cert and your calculation disagree slightly, that is usually why.
Full gauge chart
| Gauge | Steel (in) | Steel (mm) | lb/ft² | Galvanized (in) | Stainless (in) |
|---|---|---|---|---|---|
| 3 ga | 0.2391 | 6.07 | 9.76 | — | 0.2500 |
| 4 ga | 0.2242 | 5.69 | 9.16 | — | 0.2344 |
| 5 ga | 0.2092 | 5.31 | 8.54 | — | 0.2187 |
| 6 ga | 0.1943 | 4.94 | 7.94 | — | 0.2031 |
| 7 ga | 0.1793 | 4.55 | 7.32 | — | 0.1875 |
| 8 ga | 0.1644 | 4.18 | 6.71 | 0.1681 | 0.1719 |
| 9 ga | 0.1495 | 3.80 | 6.11 | 0.1532 | 0.1562 |
| 10 ga | 0.1345 | 3.42 | 5.49 | 0.1382 | 0.1406 |
| 11 ga | 0.1196 | 3.04 | 4.88 | 0.1233 | 0.1250 |
| 12 ga | 0.1046 | 2.66 | 4.27 | 0.1084 | 0.1094 |
| 13 ga | 0.0897 | 2.28 | 3.66 | 0.0934 | 0.0937 |
| 14 ga | 0.0747 | 1.90 | 3.05 | 0.0785 | 0.0781 |
| 15 ga | 0.0673 | 1.71 | 2.75 | 0.0710 | 0.0703 |
| 16 ga | 0.0598 | 1.52 | 2.44 | 0.0635 | 0.0625 |
| 17 ga | 0.0538 | 1.37 | 2.20 | 0.0575 | 0.0562 |
| 18 ga | 0.0478 | 1.21 | 1.95 | 0.0516 | 0.0500 |
| 19 ga | 0.0418 | 1.06 | 1.71 | 0.0456 | 0.0437 |
| 20 ga | 0.0359 | 0.91 | 1.47 | 0.0396 | 0.0375 |
| 21 ga | 0.0329 | 0.84 | 1.34 | 0.0366 | 0.0344 |
| 22 ga | 0.0299 | 0.76 | 1.22 | 0.0336 | 0.0312 |
| 23 ga | 0.0269 | 0.68 | 1.10 | 0.0306 | 0.0281 |
| 24 ga | 0.0239 | 0.61 | 0.98 | 0.0276 | 0.0250 |
| 25 ga | 0.0209 | 0.53 | 0.85 | 0.0247 | 0.0219 |
| 26 ga | 0.0179 | 0.45 | 0.73 | 0.0217 | 0.0187 |
| 27 ga | 0.0164 | 0.42 | 0.67 | 0.0202 | 0.0172 |
| 28 ga | 0.0149 | 0.38 | 0.61 | 0.0187 | 0.0156 |